U.S. patent number 6,599,579 [Application Number 09/514,337] was granted by the patent office on 2003-07-29 for liquid pressure transfer method , transfer film therefor and product decorated thereby.
This patent grant is currently assigned to Cubic Co., Ltd.. Invention is credited to Tomomi Kiyotaki.
United States Patent |
6,599,579 |
Kiyotaki |
July 29, 2003 |
Liquid pressure transfer method , transfer film therefor and
product decorated thereby
Abstract
A workpiece to which a transfer pattern is to be applied is
formed to have a rod-like element curved into a loop-like shape to
form an apparent geometric plane. A transfer film used in the
liquid pressure transfer is formed on a required portion thereof,
and the transfer pattern for decoration is formed to have a
configuration corresponding to that of the apparent plane. The
workpiece is handled so as to downwardly approach the transfer film
from a position corresponding to the transfer pattern, and is then
immersed in the transfer liquid. Consequently, the transfer film
bonds to the rod-like element of the workpiece so as to
circumferentially surround the rod-like element continuously from a
bottom of the rod-like element to a top thereof on the basis of a
diametric section of the rod-like element. Thus, the transfer
pattern is transferred to at least the rod-like element of the
workpiece.
Inventors: |
Kiyotaki; Tomomi (Shizuoka,
JP) |
Assignee: |
Cubic Co., Ltd. (Shizuoka,
JP)
|
Family
ID: |
17599569 |
Appl.
No.: |
09/514,337 |
Filed: |
February 28, 2000 |
Foreign Application Priority Data
|
|
|
|
|
Sep 30, 1999 [JP] |
|
|
11-278602 |
|
Current U.S.
Class: |
427/430.1;
156/230; 156/277; 427/256; 427/280 |
Current CPC
Class: |
B41M
5/025 (20130101); B62D 1/06 (20130101); Y10T
428/24802 (20150115) |
Current International
Class: |
B41M
5/025 (20060101); B62D 1/06 (20060101); B05D
005/06 (); B05D 001/18 (); B44C 001/165 () |
Field of
Search: |
;427/430.1,256,280,434.3
;156/230,240,277 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
19797/76 |
|
Jul 1977 |
|
AU |
|
19824544 |
|
Dec 1998 |
|
DE |
|
2001908 |
|
Feb 1979 |
|
GB |
|
Primary Examiner: Barr; Michael
Attorney, Agent or Firm: Wenderoth, Lind & Ponack,
L.L.P.
Claims
What is claimed is:
1. A liquid pressure transfer method comprising: supporting a
transfer film on a surface of a transfer liquid while floating the
transfer film on the surface, the transfer film having a transfer
pattern for decoration printed only on an area of the transfer film
having a shape corresponding to a surface shape of a workpiece to
be covered by the transfer pattern so that the transfer pattern has
a pattern configuration; handling the workpiece so that the
workpiece approaches the transfer film from a position above the
transfer pattern; and immersing the workpiece in the transfer
liquid so as to transfer the transfer pattern onto a surface of the
workpiece so as to decorate the workpiece, the workpiece including
a rod-shaped element curved to form a loop in a geometric plane,
the transfer pattern being printed on the transfer film such that
the pattern configuration of the transfer pattern corresponds to a
configuration of the workpiece; wherein said transferring of the
transfer pattern to the surface of the workpiece comprises bonding
the transfer film to the rod-shaped element of the workpiece so
that the transfer film circumferentially surrounds the rod-shaped
element continuously from a bottom of the rod-shaped element to a
top of the rod-shaped element with respect to a diametric
cross-section of the rod-shaped element.
2. The liquid pressure transfer method of claim 1, wherein said
handling of the workpiece comprises orienting the workpiece during
the approach of the workpiece to the transfer film so that approach
attitude angle defined between the apparent plane of the workpiece
and the surface of the transfer liquid is within a range of
.+-.15.degree..
3. The liquid pressure transfer method of claim 2, wherein the
transfer film has reference position marks thereon, further
comprising aligning the transfer pattern and the workpiece using
the reference position marks during said immersing of the
workpiece.
4. The liquid pressure transfer method of claim 2, wherein said
immersing of the workpiece comprises immersing the workpiece in the
transfer liquid in a substantially vertical direction.
5. The liquid pressure transfer method of claim 4, wherein the
transfer film has reference position marks thereon, further
comprising aligning the transfer pattern and the workpiece using
the reference position marks during said immersing of the
workpiece.
6. The liquid pressure transfer method of claim 1, wherein said
immersing of the workpiece comprises immersing the workpiece in the
transfer liquid in a substantially vertical direction.
7. The liquid pressure transfer method of claim 6, wherein the
transfer film has reference position marks thereon, further
comprising aligning the transfer pattern and the workpiece using
the reference position marks during said immersing of the
workpiece.
8. The liquid pressure transfer method of claim 1, wherein the
transfer film has reference position marks thereon, further
comprising aligning the transfer pattern and the workpiece using
the reference position marks during said immersing of the
workpiece.
9. The liquid pressure transfer method of claim 1, wherein the
transfer pattern has a substantially annular pattern configuration
corresponding to the steering wheel.
10. The liquid pressure transfer method of claim 1, further
comprising: gathering a first group of pattern data for a planar
rectangular-shaped pattern and converting the first group of
pattern data into a second group of pattern data for a round-shaped
pattern; and forming the transfer pattern on the transfer film
using the second group of pattern data so that the transfer pattern
has a substantially annular pattern configuration.
11. The liquid pressure transfer method of claim 1, wherein said
transferring of the transfer pattern onto the surface of the
workpiece comprises bonding the transfer film to the workpiece so
that the transfer pattern entirely surrounds the rod-shaped element
of the workpiece.
12. A liquid pressure transfer method comprising: forming a
transfer film having a transfer pattern for decoration printed only
on an area of the transfer film having a shape corresponding to a
surface shape of a workpiece to be covered by the transfer film the
transfer pattern so that the transfer pattern has a pattern
configuration, the transfer pattern being printed on the transfer
film such that the pattern configuration of the transfer pattern
corresponds to a configuration of the workpiece including a
rod-shaped element curved to form a loop in a geometric plane;
supporting the transfer film on a surface of a transfer liquid
while floating the transfer film on the surface; handling the
workpiece so that the workpiece approaches the transfer film from a
position above the transfer pattern; and immersing the workpiece in
the transfer liquid so as to transfer the transfer pattern onto a
surface of the workpiece so as to decorate the workpiece; wherein
said transferring of the transfer pattern onto the surface of the
workpiece comprises bonding the transfer film to the rod-shaped
element of the workpiece so that the transfer film
circumferentially surrounds the rod-shaped element continuously
from a bottom of the rod-shaped element to a top of the rod-shaped
element with respect to a diametric cross-section of the rod-shaped
element.
13. The liquid pressure transfer method of claim 12, wherein the
workpiece comprises a steering wheel, said forming of the transfer
film having the transfer pattern printed thereon comprises printing
the transfer pattern on the transfer film so that the transfer
pattern has a substantially annular pattern configuration
corresponding to a geometric plane of the steering wheel.
14. The liquid pressure transfer method of claim 13, further
comprising: gathering a first group of pattern data for a planar
rectangular-shaped pattern and converting the first group of
pattern data into a second group of pattern data for a round-shaped
pattern; and said printing of the transfer pattern on the transfer
film comprises printing the transfer pattern on the transfer film
using the second group of pattern data so as to form the transfer
pattern having the substantially annular pattern configuration.
15. The liquid pressure transfer method of claim 13, wherein said
handling of the workpiece comprises orienting the workpiece during
the approach of the workpiece to the transfer film so that an
approach attitude angle defined between the apparent plane of the
workpiece and the surface of the transfer liquid is within a range
of .+-.15.degree..
16. The liquid pressure transfer method of claim 13, wherein said
immersing of the workpiece comprises immersing the workpiece in the
transfer liquid in a substantially vertical direction.
17. The liquid pressure transfer method of claim 13, wherein said
forming of the transfer film includes forming reference position
marks on the transfer film, further comprising aligning the
transfer pattern and the workpiece using the reference position
marks during said immersing of the workpiece.
18. The liquid pressure transfer method of claim 12, wherein said
handling of the workpiece comprises orienting the workpiece during
the approach of the workpiece to the transfer film so that an
approach attitude angle defined between the apparent plane of the
workpiece and the surface of the transfer liquid is within a range
of .+-.15.degree..
19. The liquid pressure transfer method of claim 12, wherein said
forming of the transfer film includes forming reference position
marks on the transfer film, further comprising aligning the
transfer pattern and the workpiece using the reference position
marks during said immersing of the workpiece.
20. The liquid pressure transfer method of claim 12, wherein said
immersing of the workpiece comprises immersing the workpiece in the
transfer liquid in a substantially vertical direction.
21. The liquid pressure transfer method of claim 12, further
comprising: gathering a first group of pattern data for a planar
rectangular-shaped pattern and converting the first group of
pattern data into a second group of pattern data for a round-shaped
pattern; and said printing of the transfer pattern on the transfer
film comprises printing the transfer pattern on the transfer film
using the second group of pattern data so that the transfer pattern
has a substantially annular pattern configuration.
22. The liquid pressure transfer method of claim 12, wherein said
transferring of the transfer pattern onto the surface of the
workpiece comprises bonding the transfer film to the workpiece so
that the transfer pattern entirely surrounds the rod-shaped element
of the workpiece.
Description
BACKGROUND OF THE INVENTION
This invention relates to a liquid pressure transfer method, and
more particularly to a liquid pressure transfer printing method for
applying a pattern for decoration specifically intended for a
workpiece such as a steering wheel for an automobile or the like
which includes a rod-like element curved to form a predetermined
apparent plane to the workpiece.
For example, a steering wheel for an automobile has a core made of
a metal material so as to exhibit strength of at least a
predetermined level. The core is provided therearound with a grip
surface, which is formed of a material such as a plastic material,
a wooden material, a leather material or the like, which is
selected depending on requirements such as operability of the
steering wheel, decorative characteristics thereof and the like.
For example, a steering wheel provided thereon with a wooden
surface is evaluated to be a high-quality article, because it
exhibits both satisfactory operability and decorative
characteristics and requires considerable labor and time for
manufacturing. However, a recent tendency to reconsider the
easygoing use of a natural material in view of protecting the
natural environment, and a demand for reduction of a manufacturing
cost had led to development of liquid pressure transfer printing
techniques. These techniques involve transfer printing on a plastic
steering wheel material in place of a wooden steering wheel
material to apply a woodgrain pattern for decoration thereto.
Application of a decorative pattern to a workpiece by liquid
pressure transfer permits formation of a natural pattern which
exhibits satisfactory conformability to a configuration of the
workpiece, resulting in the technique being extensively practiced
on a variety of workpieces. However, application of such liquid
pressure transfer to, for example, a steering wheel encounters some
important problems. A conventional steering wheel made of a wooden
material is manufactured by subjecting two wooden rod-like
materials which are semicircular in section to a treatment by
moistening and heating to bend them into an annular shape, and then
bonding them to each other while interposing a core therebetween.
Thus, of course the wooden materials are each so arranged that a
straight grain extends in a circumferential direction of the
steering wheel. Such arrangement of the straight grain permits a
user to have a sense of security or a sense of reliability.
Unfortunately, in application of a decorative pattern to a
workpiece by liquid pressure transfer, a transfer film having a
transfer pattern formed thereon is supported on a surface of a
transfer liquid while being floated thereon, so that exact
positioning or registration between the transfer film and the
workpiece is relatively difficult. Thus, in the prior art, a
continuously-formed decorative pattern such as a woodgrain pattern,
a natural stone pattern, or a carbon fiber pattern is arranged all
over the transfer film so as to allow misregistration which occurs
between the transfer film and the workpiece. Consequently, a
decorative pattern similar to a natural material is provided
irrespective of a portion of the pattern transferred to the
workpiece. Nevertheless, development of techniques of reproducing a
transfer pattern specifically intended for a desired product such
as, for example, techniques of arranging a straight grain pattern
in a circumferential direction of a steering wheel, are still
demanded.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing
disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a
liquid pressure transfer method which is capable of applying a
decorative pattern specifically intended for a specific or desired
workpiece such as a steering wheel or the like to the
workpiece.
It is another object of the present invention to provide a transfer
film which is capable of facilitating application of a decorative
pattern specifically intended for a workpiece such as a steering
wheel or the like to the workpiece.
It is a further object of the present invention to provide a
product decorated according to the liquid pressure transfer method
described above.
In accordance with one aspect of the present a liquid pressure
transfer method for carrying out liquid pressure transfer printing
on a workpiece such as a steering wheel is provided. The liquid
pressure transfer method includes the step of supporting a transfer
film on a surface of a transfer liquid while floating it thereon.
The transfer film has a transfer pattern for decoration printed
thereon. The liquid pressure transfer method also includes the step
of downwardly immersing a workpiece in the transfer liquid to
transfer the transfer pattern to a surface of the workpiece, to
thereby decorate the workpiece. The workpiece includes a rod-like
element curved into a loop-like shape, resulting in it being formed
in an apparent geometric plane which permits the workpiece to be
recognized as a whole. The transfer pattern is formed to have a
configuration corresponding to a configuration of the apparent
plane of the workpiece, and is arranged on a required position of
the transfer film. The workpiece is handled so as to approach the
transfer film from a position above the transfer pattern
corresponding to the transfer pattern and is then immersed in the
transfer liquid. Therefore, the transfer film bonds to the rod-like
element of the workpiece in a manner to circumferentially surround
the rod-like element continuously from a bottom of the rod-like
element to a top thereof on the basis of a diametric section of the
rod-like element, resulting in the transfer pattern being
transferred to at least the rod-like element of the workpiece.
The liquid pressure transfer method thus constructed permits the
workpiece, such as a steering wheel or the like which includes the
rod-like element curved to form a predetermined apparent plane, to
be readily and positively decorated with a transfer pattern
specifically intended for the workpiece.
In a preferred embodiment of the present invention, an approach
attitude angle defined between the apparent plane of the workpiece
and the surface of the transfer liquid is set to be within a range
of .+-.15.degree.. This permits the optimum approach attitude angle
to be set depending on a type of the transfer pattern, as well as a
size of the workpiece, a configuration thereof and the like.
In a preferred embodiment of the present invention, the workpiece
is immersed in the transfer liquid in a substantially vertical
direction. Such vertical lowering of the workpiece to the surface
of the transfer liquid facilitates transfer of the transfer pattern
to the workpiece.
In a preferred embodiment of the present invention, the transfer
film is provided thereon with reference position marks for enabling
relative registration between the transfer pattern and the
workpiece. This permits positioning or registration between the
transfer pattern and the workpiece to be readily attained while
preventing misregistration of the transfer film.
In accordance with another aspect of the present invention, a
transfer film is provided. The transfer film includes a film body
which has a transfer operation surface defined thereon. The
transfer operation surface has a predetermined transfer pattern
previously printed thereon in transfer ink. When transfer is to be
carried out, the transfer operation surface is coated thereon with
an activator to permit a portion of the transfer operation surface
to which the transfer ink is applied to exhibit stickiness. The
transfer film is supported on a surface of a transfer liquid while
being floated thereon. The transfer pattern is transferred to a
surface of a workpiece by a liquid pressure produced when the
workpiece is downwardly immersed in the transfer liquid. The
transfer film is applied to the workpiece including a rod-like
element curved into a loop-like shape, resulting in the workpiece
being formed with an apparent plane which permits the workpiece to
be recognized as a whole. The transfer pattern is formed to have a
configuration corresponding to a configuration of the apparent
plane of the workpiece and arranged on a required position of the
transfer film. The transfer film thus constructed permits the
transfer pattern specifically intended for the workpiece to be
readily applied to the workpiece, to thereby facilitate decoration
of the workpiece.
In a preferred embodiment of the present invention, the workpiece
is a steering wheel. The transfer pattern is formed to have a
substantially annular shape in correspondence to the apparent plane
of the steering wheel. Thus, in the present invention, although
distortion of the pattern is varied depending on a position on a
circumference of a diametric section of the rod-like element of the
workpiece, the pattern distortion in a circumferential direction of
the whole steering wheel is substantially the same irrespective of
a position on the rod-like element in the circumferential direction
thereof. Thus, the transfer printing may be carried out while
rendering the pattern distortion inconspicuous.
In a preferred embodiment of the present invention, the transfer
pattern is formed to have a substantially annular shape by taking
in pattern data having a plane rectangular shape and then
converting the pattern data into pattern data having a round shape.
This permits the transfer pattern specifically intended for the
workpiece to be more exactly reproduced on the workpiece.
In accordance with a further aspect of the present invention, there
is provided a decorated product to which a predetermined decorative
pattern is applied by subjecting a workpiece such as a steering
wheel or the like including a rod-like element to liquid pressure
transfer printing in which the workpiece is downwardly immersed in
a transfer liquid which supports a transfer film having a transfer
pattern for decoration printed on a surface thereof while floating
it on the transfer liquid. Therefore, the transfer pattern is
applied to at least the rod-like element of the workpiece. The
workpiece is operated so as to permit the transfer pattern to be
printed on the rod-like element of the workpiece in a manner to
circumferentially surround the rod-like element continuously from a
bottom of the rod-like element to a top thereof on the basis of a
diametric section of the rod-like element. Consequently, transfer
of the transfer pattern to the workpiece is carried out according
to the above-described liquid pressure transfer method while
ensuring exact reproducibility of the transfer pattern.
Such construction permits the transfer pattern to be more exactly
reproduced on a variety of workpieces of a closed loop shape or an
open loop shape including, for example, a hula hoop, rings in
gymnastic, a towel ring, a chair back, a handrail and the like in
addition to the steering wheel while minimizing distortion of the
transfer pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and many of the attendant advantages of the
present invention will be readily appreciated as the same becomes
better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings; wherein:
FIG. 1A is a schematic side elevation view showing an apparatus
which is adapted to practice a liquid pressure transfer method
according to the present invention, wherein an immersion angle is
set to be 0.degree. by way of example;
FIG. 1B is an enlarged partial cross sectional view of part 1B of
FIG. 1A;
FIG. 2 is a schematic side elevation view showing the apparatus
which is adapted to practice a liquid pressure transfer method
according to the present invention, the immersion angle is set to
be 20.degree.;
FIGS. 3A to 3C are plan views showing a transfer pattern formed on
a transfer film;
FIG. 4A is a perspective view showing a steering wheel which is an
example of a decorated product according to the present
invention;
FIG. 4B is a sectional view taken along line 4B--4B of FIG. 4A;
FIGS. 5A to 5C are schematic views showing steps of liquid pressure
transfer by stages, respectively;
FIG. 6 is a schematic side elevation view showing a unit for
continuously feeding a transfer film to a transfer bath, in which a
transfer liquid flows; and
FIG. 7 is a schematic view showing a procedure for converting
pattern data of a rectangular shape into pattern data of an annular
shape.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, the present invention will be described in detail with
reference to the accompanying drawings. The following description
will be first made on a workpiece to be decorated according to the
present invention. Then, a liquid pressure transfer printing
apparatus for carrying out liquid pressure transfer printing on
such a workpiece is schematically described. Subsequently, a liquid
pressure transfer printing method according to the present
invention will be described together with a manner of operation of
the liquid pressure transfer printing apparatus.
A workpiece designated by reference character W in FIGS. 1A, 1B and
2 includes a rod-like element formed to be curved to define a
predetermined apparent geometric plane R which permits the
workpiece to be recognized as a whole. Thus, the workpieces to
which the present invention is applicable may include, for example,
a steering wheel mounted on a vehicle or the like, as well as
products of an annular shape, a substantially O-shape or the like
which form a closed loop such as a hula hoop, rings in gymnastics,
a towel ring and the like, and products of a substantially U-shape
which form an open loop such as a chair back and the like. Further,
the workpieces may include products such as a handrail for stairs
and the like wherein two loop-like members are connected together
through one or two straight members.
The apparent plane R is defined as a plane literally when the
present invention is applied to a steering wheel as the workpiece
W. However, it is not necessarily defined as a plane when the
present invention is applied to a chair back as the workpiece W. In
that case, the apparent plane R may be often defined so as to
somewhat have a curvature.
Also, the illustrated embodiment will be described essentially in
connection with the case that the present invention is applied to a
steering wheel as the workpiece W. Thus, when it is necessary to
distinguish a steering wheel before the liquid pressure transfer
printing of the present invention from a steering wheel after the
transfer printing, a steering wheel which has been subjected to the
liquid pressure transfer printing is designated by reference
character 1, and a steering wheel before the printing is designated
by 1A.
Now, the steering wheel 1 which has been subjected to the liquid
pressure transfer printing will be described with reference to
FIGS. 4A and 4B by way of example. The steering wheel 1 includes a
boss section 2 acting as a center of rotational movement of the
steering wheel 1, spoke sections 3 arranged so as to radially
extend from the boss section 2, and a rim section 4 connected to a
distal end of each of the spoke sections 3 and formed to have a
substantially annular shape. The rim section 4, as shown in FIG.
4A, includes a long rim portion 41 of an elongated arcuate shape
(positioned on an upper side in FIG. 4A), a short rim portion 42 of
a short arcuate shape (positioned on a lower side in FIG. 4A), and
two grip portions 43 for connecting the long rim portion 41 and
short rim portion 42 to each other therethrough (positioned on both
lateral sides in FIG. 4A). The long rim portion 41 and short rim
portion 42 have a transfer pattern P specifically intended for the
workpiece W such as a woodgrain pattern, a straight grain pattern
or the like, applied thereto and is formed thereon with a
topcoat.
The grip portions 43 are each connected to the spoke sections 3
which extend from the boss section 2. It is considered that the
spoke sections 3 cause force which is different from that acting on
the other portions, such as the long rim portion 41 and short rim
portion 42, to act on the transfer film F during the transfer. This
prevents liquid pressure transfer printing like that carried out on
the other portions to be attained on the grip portions 43. Thus,
for example, techniques of wrapping a suitable material such as
leather or the like around the grip portions 43 may be employed
after transfer printing, to thereby hide printing applied to the
grip portions 43 or to apply a special decoration effect or a grip
feel to the grip portions. However, unless printing applied to the
grip portions 43 adversely affects an appearance of the product or
causes any problem, such techniques may be eliminated. Also, when
it is not desired to apply liquid pressure transfer printing to the
grip portions 43, they may be covered with any suitable masking
material in advance.
In printing applied to the rim section 4, the transfer pattern P
specifically intended for the workpiece W or steering wheel 1A is
transferred to the rim section 4, wherein the illustrated
embodiment permits pattern distortion to be inconspicuous as
compared with the prior art. This is due to the fact that the
transfer pattern P is substantially formed to have an annular shape
corresponding to a configuration of the steering wheel 1A. More
particularly, in a diametric section of the rod-like element of the
steering wheel 1A or a section of the rod-like element of the
steering wheel taken in a diametric direction of the rod-like
element, distortion of the transfer pattern P is varied depending
on a position on a circumference of the diametric section of the
rod-like element. However, the pattern distortion in a
circumferential direction of the whole steering wheel 1A is
substantially the same irrespective of positions thereof. This
permits the pattern distortion on the whole steering wheel 1A to be
inconspicuous as a whole. The transfer pattern P is so arranged
that a joint line Pa of the transfer pattern P is positioned on a
rear surface of the steering wheel 1 which is substantially out of
sight of a driver when the steering wheel is mounted in a
vehicle.
Now, a liquid pressure transfer printing apparatus 10 will be
described with reference to FIG. 1A by way of example. The liquid
pressure transfer printing apparatus 10 includes a transfer bath
11, a transfer film storage unit (not shown) and a workpiece
holding unit 13.
The transfer bath 11 has a transfer liquid L stored therein, and a
transfer film F is supported on a surface of the transfer liquid L
while being floated thereon. In the illustrated embodiment, the
transfer films formed in individual sheets are fed to the transfer
bath 11 one by one by hand so as to be floated on the transfer
liquid L, so that the transfer liquid L is always kept
stationary.
The transfer film storage unit is constructed so as to permit the
transfer films F to be taken out thereof one by one.
The transfer film F may be formed to have a rectangular
configuration as shown in each of FIGS. 3A to 3C by way of example.
The transfer film F includes a film body which has a transfer
operation surface defined thereon. The transfer operation surface
has the transfer pattern P for decoration formed only on a required
position thereof corresponding to a configuration of the apparent
plane R of the workpiece W. In the illustrated embodiment, the
transfer pattern P is formed to have a substantially annular shape
corresponding to the configuration of the rim section 4 of the
steering wheel 1. Also, the transfer film F is suitably provided
thereon with reference position marks M which permit relative
positioning or registration between the transfer pattern P and the
workpiece W to be carried out therethrough. In the illustrated
embodiment, the reference position marks M include a cross-like
mark arranged on a substantially central position of the transfer
pattern, four radial marks arranged at substantially equal angular
intervals on an outside of the transfer pattern P, and the like by
way of example, as shown in each of FIGS. 3A to 3C.
A transfer film F shown in FIG. 3A is adapted to be directed to
decoration of the workpiece W carried out when the workpiece W is
vertically lowered to the surface of the transfer liquid L while
maintaining an approach attitude angle .beta. of the workpiece W at
0.degree.. The transfer film F of FIG. 3A has a transfer pattern P
of a substantially concentric shape formed thereon with high
accuracy. A transfer film F shown in FIG. 3B is directed to the
decoration when the workpiece W is vertically lowered to the liquid
surface while maintaining the approach attitude angle .beta. at
suitable degrees. Thus, the transfer film F of FIG. 3B corresponds
to that shown in FIG. 1. The transfer film F of FIG. 3B has a
transfer pattern P which is formed to have a substantially annular
shape provided thereon, wherein a major axis Ac and a minor axis At
thereof extend in a vertical direction and a horizontal direction
of FIG. 3B, respectively. A transfer film F shown in FIG. 3C is
directed to decoration of the workpiece W when it is obliquely
lowered to the liquid surface while maintaining an approach
attitude angle (a thereof at suitable degrees. The transfer film F
corresponds to that described hereinafter with reference to FIG. 2.
Thus, the transfer film F of FIG. 3C has a transfer pattern P
formed to have a substantially annular shape, wherein a minor axis
At and a major axis Ac thereof extend in a vertical direction and a
horizontal direction of FIG. 3C, respectively. The term
"substantially annular shape " referred to herein indicates such
configurations as shown in FIGS. 3A to 3C. Thus, the substantially
annular shapes include a substantially complete annular shape as
shown in FIG. 3A, as well as somewhat deformed annular shapes as
shown in FIGS. 3B and 3C. Therefore, as seen in the attached
drawings, the transfer pattern is printed only on an area of the
transfer film F that has a shape corresponding to a surface shape
of the workpiece W to be covered by the transfer pattern. Also, the
transfer film F shown in each of FIGS. 3A to 3C has only one
transfer pattern P printed thereon. Alternatively, the transfer
film may have a plurality of transfer patterns P printed
thereon.
Further, forming the transfer pattern P into a substantially
annular shape for the purpose of transferring, for example, a
woodgrain pattern to the workpiece is carried out by subjecting an
image of a woodgrain actually photographed to image processing by
means of a computer or preparing a picture of a woodgrain directly
by means of a computer, to thereby convert a pattern to be
transferred into pattern data of a plane rectangular shape. Then,
the plane rectangular pattern data thus converted are converted
into pattern data of a round or ring-like shape on the computer,
resulting in the transfer pattern P being formed to have a
substantially annular shape. Thus, it will be noted that when the
plane rectangular pattern before the conversion is represented in a
coordinate system containing X and Y coordinate axes which are
perpendicular to each other as shown in FIG. 7, the conversion
permits the X axis to be converted into a circumferential direction
and the Y axis to be converted into a radial direction, resulting
in the transfer pattern P of a substantially annular shape being
provided. Of course, the operation of joining opposite ends of the
plane rectangular shape to each other is carried out with suitable
image processing for rendering the joint inconspicuous, such as
connecting woodgrain lines to each other.
The above description has been made for conversion of the transfer
pattern into a round shape carried out immediately after taking in
the transfer pattern as the pattern data of a plane rectangular
shape. However, for example, it is considered that the pattern data
photographed may be too small to be developed in the
circumferential direction. More particularly, the pattern data of a
plane rectangular shape indicated by solid lines shown in FIG. 7
have a dimension in the X axis direction sufficient to be converted
into the circumferential direction. However, the pattern data
having such a large size is not necessarily photographed. In order
to solve the problem, an approach may be employed which is
constructed so as to introduce pattern data of a small size readily
photographed into an image processing unit and to repeat the
pattern data to prepare plane rectangular pattern data of a desired
large size.
Another approach which may be employed is to introduce pattern data
of a small size into an image processing unit and then
independently multiply a longitudinal dimension of the pattern data
and a lateral dimension thereof on a screen of the unit to obtain
plane rectangular pattern data of a desired size. Repeating of such
small-sized pattern data for formation of such plane rectangular
pattern data of a desired size may be carried out on the same
pattern. Alternatively, patterns different from each other may be
connected to each other. The operation of multiplying the
longitudinal dimension and lateral dimension independently from
each other is effective to not only convert the pattern data into a
desired size but also, for example, to set the density of woodgrain
lines at a suitable level.
The workpiece holding unit 13 functions to immerse the steering
wheel 1A into the transfer liquid L while holding it. In the
immersion, an approach attitude angle a defined between the
apparent plane R of the workpiece W and the surface of the transfer
liquid L is set to be within a range of .+-.15.degree. based on a
horizontal direction. The symbols "+" and "-" referred to herein do
not have any specific definition. They merely mean that one
rotational direction from a certain reference position indicates
"+" and the other rotational direction indicates "-". Also, in the
illustrated embodiment, the workpiece W is immersed in the transfer
liquid L in a vertical direction as shown in FIG. 1A. However, a
direction of immersion of the workpiece W may be suitably varied.
In the present invention, the direction of immersion is indicated
by an angle .beta. between the direction of immersion and a line
normal to the surface of the transfer liquid, which angle is
defined to be an immersion angle herein. When the workpiece is
immersed in the normal direction as shown in FIG. 1A, the immersion
angle is defined to be 0.degree., that is, the workpiece is
vertically lowered. The approach attitude angle a and immersion
angle .beta. are each suitably set depending on various factors
such as a size of the transfer pattern P, a size of the steering
wheel 1A, a thickness of the rod-like element, and the like.
However, the angles set are not necessarily kept constant during
transfer of the transfer pattern to the workpiece. For example,
when the apparent plane R of the workpiece W somewhat has a
curvature, the angle may be suitably varied after start of the
immersion. For example, in the immersion shown in FIG. 2, the
approach attitude angle .alpha. and immersion angle .beta. are set
to be 10.degree. and 20.degree., respectively.
Now, liquid pressure transfer printing on the workpiece such as a
steering wheel or the like will be described in relation to
operation of the liquid pressure transfer printing apparatus 10
thus constructed.
(1) Feeding of the Transfer Film:
First, the transfer film F is fed onto the transfer liquid L in the
transfer bath 11 while an activator is coated on a surface of the
transfer film F to which a transfer ink is applied. The activator
may be made by, for example, mixing a resin material, a pigment, a
solvent, a plasticizer and the like with each other at suitable
ratios. Alternatively, a solvent such as a thinner or the like may
be merely used as the activator. Thus, the term "activators "
referred to herein include a thinner and the like. The transfer
film F thus coated thereon with the activator absorbs water, to
thereby be softened and swollen, resulting in it somewhat extending
in all directions. Coating of the activator on the transfer film F
is necessary because the transfer film F is normally stored while
the applied transfer ink is kept dry. Thus, the coating permits the
ink coated surface of the transfer film F to be provided with
stickiness, so that the ink on the transfer film F may be
transferred. Also, coating of the activator on the transfer film F
may be carried out after feeding of the transfer film F onto the
transfer liquid L as well. Thus, the terms "the activator is coated
on the transfer film to provide the ink coated surface of the
transfer film with stickiness and permit the transfer film to be
floated on the transfer liquid" referred to herein or an expression
similar thereto does not limit the steps to any specific order.
Thus, in the present invention, coating of the activator may be
carried out either after floating of the transfer film F on the
transfer liquid or prior thereto.
(2) Feeding of Steering Wheel:
The workpiece W or steering wheel 1A is set so that a front surface
thereof (defined by the time when it is mounted in a vehicle) is
kept facing the transfer film F. This permits the joint line Pa of
the transfer film F to be positioned on a side of a rear surface of
the steering wheel which is substantially out of sight of a driver.
Then, the steering wheel 1A is immersed in the transfer liquid L
while being suitably maintained at an approach attitude angle
.alpha. and an inversion angle .beta. by the workpiece holding unit
13. The approach attitude angle .alpha. and immersion angle .beta.
are not necessarily kept constant during the transfer. The angles
.alpha. and .beta. may be suitably varied depending on the apparent
plane R formed or the like after the start of the immersion as
well. Also, the transfer film F, as described above, may be
provided thereon with the reference position marks M for relative
registration between the transfer pattern P and the workpiece W.
Such arrangement of the reference position marks M permits a
position at which immersion of the steering wheel 1A is started to
be readily determined.
(3) Transfer:
When the steering wheel 1A is immersed in the transfer liquid L,
the transfer film F is continuously bonded to the steering wheel
1A, so that the transfer pattern P may be transferred to the
steering wheel 1A while keeping distortion of the pattern P
inconspicuous. The transfer may be carried out as shown in FIGS. 5A
to 5C by way of example. More particularly, the transfer film F
circumferentially surrounds the rod-like element continuously from
a bottom of the rod-like element to a top thereof on the basis of a
diametric section of the rod-like element with progress of
immersion of the steering wheel 1A in the transfer liquid L, so
that the transfer film F ultimately forms the joint line Pa when it
reaches the rear surface side of the steering wheel 1A. Then, the
joint line Pa is formed on a whole circumference of the rear
surface of the steering wheel 1A, resulting in the transfer being
substantially completed.
Now, distortion of the transfer pattern P on the steering wheel 1A
will be described. First, it is supposed that on a circumference of
the diametric section of the rod-like element of the steering wheel
1A, a lowermost point at which the transfer is first initiated, an
uppermost point at which the joint line Pa of the transfer pattern
P is formed, an innermost peripheral point positioned between the
lowermost point and the uppermost point, and an outermost
peripheral point positioned therebetween are designated by
reference characters P0, P1, P2 and P3 in FIG. 1B, respectively. In
this instance, in a region in which the transfer is carried out
from the lowermost point P0 through the innermost peripheral point
P2 to the uppermost point P1, a radius of the rod-like element
projected on a horizontal plane is gradually decreased from the
lowermost point P0 to the innermost peripheral point P2 and
gradually increased from the innermost peripheral point P2 to the
uppermost point P1. Consequently, in a region where the transfer is
carried out from the lowermost point P0 through the outermost
peripheral point P3 to the uppermost point P1, the radius of the
rod-like element projected on a horizontal plane is gradually
increased from the lowermost point P0 to the outermost peripheral
point P3 and gradually decreased from the outermost peripheral
point P3 to the uppermost point P1.
In order to eliminate distortion of the transfer pattern over the
whole circumference or periphery of the diametric section of the
rod-like element of the steering wheel 1A, the transfer pattern P
would be preferably formed so as to permit such a radius of the
rod-like element projected on a horizontal plane to be
substantially exactly reproduced. However, this is highly
difficult. Therefore, the actual transfer pattern P to be printed
is formed to have a substantially annular shape so that the radius
projected on a horizontal plane is increased in one direction
toward an outside of the transfer pattern. This of course causes
the transfer pattern to be subject to distortion, so that a degree
of pattern distortion on the circumference or periphery of the
diametric section of the rod-like element is of course varied
depending on a position on the circumference of the section.
However, the transfer film F is softened and swollen due to
immersion thereof in the transfer liquid L, resulting in
substantially extending in all directions, so that the lowermost
point P0, uppermost point P1, innermost peripheral point P2 and
outermost peripheral point P3 are substantially identical in
pattern distortion in a peripheral or circumferential direction of
the whole rod-like element with each other. This permits the
pattern distortion on the whole steering wheel 1A to be
inconspicuous.
(4) Removal of film and drying:
The steering wheel 1A which has been thus subjected to the liquid
pressure transfer printing has a residue of the transfer film F
which has not been dissolved in the transfer liquid L adhered
thereto. Thus, in order to fully remove the residue, the steering
wheel 1A is subjected to washing by showering or the like, followed
by drying.
(5) Topcoat
The steering wheel 1A having the transfer pattern thus printed
thereon provides the decorated product of the present invention.
However, when it is desired that a portion of the steering wheel
which has been subjected to the transfer printing exhibit increased
gloss and depth of a color, a transparent topcoat is formed thereon
by spraying or the like. The topcoat thus formed may be subjected
to polishing by buffing or the like.
In the illustrated embodiment, the transfer films F formed in
individual sheets are fed one by one by hand to the transfer bath
11 in which the transfer liquid L is kept stationary so that they
may be floated on the transfer liquid L. Alternatively, the present
invention may be constructed in such a manner that a transfer film
F is continuously fed to the transfer bath 11 in which the transfer
liquid L is kept flowing. In this instance, the steering wheel 1A
may be vertically lowered to the transfer bath 11. Alternatively,
the steering wheel may be obliquely lowered to the transfer bath by
means of a conveyor of an inverted triangular configuration, an
articulated robot or the like. Also, coating of the active agent on
the transfer film F may be carried out either before feeding of the
transfer film F to the transfer bath 11 or thereafter.
Referring now to FIG. 6, another embodiment of the present
invention is illustrated. The embodiment shown in FIG. 6 is
constructed so as to continuously feed a transfer film F to a
transfer bath 11. For this purpose, the transfer bath 11 is
provided thereon with a circulation pipe line 14 and a pump 15, so
that a transfer liquid L may be slowly circulated as indicated by
an arrow in FIG. 6. Also, the transfer bath 11 is provided on each
of opposite side ends thereof with a guide chain 16. Further, the
transfer bath 11 is provided with a fan unit 17, which is
positioned on an upstream side of the transfer liquid L. Thus, the
transfer liquid L circulated, the guide chains 16, the fan unit 17
and the like cooperate with each other to permit the transfer film
F floatedly supported on a surface of the transfer liquid L to be
carried toward a workpiece W or a steering wheel 1A while
preventing waves from forming in the transfer liquid L.
Also, in the illustrated embodiment, a transfer film feed unit 12
is substituted for the transfer film storage unit incorporated in
the embodiment described above. The transfer film feed unit 12
includes a film roll 18 constituted by winding a water-soluble
transfer film F in a roll-like manner, a solvent tank 19 having an
activator S stored therein, and feed rollers 20. The transfer film
F delivered from the film roll 18 is activated by the activator S
in the solvent tank 19 and then continuously fed to the transfer
bath 11.
After the transfer film F fed to the transfer bath 11 which is thus
activated is carried to a suitable position, the steering wheel 1A
is immersed in the transfer bath 11 by means of a workpiece holding
unit 13. Operation of transferring a transfer pattern P from the
transfer film F to the workpiece W in the illustrated embodiment is
carried out in substantially the same manner as that in the
embodiment described above.
As can be seen from the foregoing, the present invention permits
the workpiece such as a steering wheel or the like including the
rod-like element curved to form the apparent plane to be readily
and positively decorated with the transfer pattern specifically
intended for the workpiece.
Also, the present invention permits the approach attitude angle
and/or immersion angle to be optimally set depending on a type of
the transfer pattern, as well as a size of the workpiece, a
configuration thereof and the like.
Further, positioning or registration between the transfer pattern
of the transfer film floatedly supported on the transfer liquid and
the workpiece is relatively readily attained, to thereby prevent
misregistration of the transfer film.
Moreover, distortion of the pattern is varied depending on a
position on the periphery of the diametric section of the rod-like
element of the workpiece. However, the pattern distortion is
substantially the same irrespective of a position on the
circumference of the whole rod-like element. Thus, the transfer
printing may be carried out while rendering the pattern distortion
inconspicuous.
While preferred embodiments of the invention have been described
with reference to the drawings, obvious modifications and
variations are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced other than as specifically
described.
* * * * *